Identification of critical residues for heterodimerization within the ligand-binding domain of retinoid X receptor

S. K. Lee, S. Y. Na, H. J. Kim, J. Soh, H. S. Choi, Woon Lee Jae Woon Lee

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28 Scopus citations


Nuclear receptors regulate transcription by binding to specific DNA response elements as homodimers or heterodimers with the retinoid X receptors (RXRs). The identity box (I-box), a 40- amino acid region within the ligand-binding domains of RXRs and other nuclear receptors, was recently shown to determine identity in the heterodimeric interactions. Here, we dissected this region in the yeast two-hybrid system by analyzing a series of chimeric receptors between human RXRα and rat hepatocyte nuclear factor 4 (HNF4), a distinct member of the nuclear receptor superfamily that prefers homodimerization. We found that the C-terminal 11-amino acid region of the RXR I-box was sufficient to direct chimeric receptors based on the HNF4 ligand-binding domain to heterodimerize with retinoic acid receptors or thyroid hormone receptors. Furthermore, we identified the hRXRα amino acids A416 and R421 of the 11-amino acid subregion as most critical determinants of heterodimeric interactions; i.e. mutant HNF4s incorporating only the hRXRα A416 or R421 heterodimerized with retinoic acid receptor.

Original languageEnglish (US)
Pages (from-to)325-332
Number of pages8
JournalMolecular Endocrinology
Issue number3
StatePublished - Jan 1 1998


ASJC Scopus subject areas

  • Molecular Biology
  • Endocrinology

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